The Greased Tyres powerup affects the tyres' grip. It makes them act as if they were covered in grease, meaning that they slide around rather than moving the car. It has a similar effect to when a vehicle is trapped in a puddle of mud and can't get out, except that this powerup still makes the car move, albeit not much.

In Carmageddon II, the cheat code is WOTATWATAMI. Read as "What a twat am I", this is presumably a comment on the negative opinion of lower class show-offs doing doughnuts, as if they could not control their vehicles due to having greased tyres.